Previous: dorg2l Up: ../lapack-d.html Next: dorgbr

dorg2r

 NAME
      DORG2R - generate an m by n real matrix Q with orthonormal
      columns,

 SYNOPSIS
      SUBROUTINE DORG2R( M, N, K, A, LDA, TAU, WORK, INFO )

          INTEGER        INFO, K, LDA, M, N

          DOUBLE         PRECISION A( LDA, * ), TAU( * ), WORK( *
                         )

 PURPOSE
      DORG2R generates an m by n real matrix Q with orthonormal
      columns, which is defined as the first n columns of a pro-
      duct of k elementary reflectors of order m

            Q  =  H(1) H(2) . . . H(k)

      as returned by DGEQRF.

 ARGUMENTS
      M       (input) INTEGER
              The number of rows of the matrix Q. M >= 0.

      N       (input) INTEGER
              The number of columns of the matrix Q. M >= N >= 0.

      K       (input) INTEGER
              The number of elementary reflectors whose product
              defines the matrix Q. N >= K >= 0.

      A       (input/output) DOUBLE PRECISION array, dimension (LDA,N)
              On entry, the i-th column must contain the vector
              which defines the elementary reflector H(i), for i =
              1,2,...,k, as returned by DGEQRF in the first k
              columns of its array argument A.  On exit, the m-
              by-n matrix Q.

      LDA     (input) INTEGER
              The first dimension of the array A. LDA >= max(1,M).

      TAU     (input) DOUBLE PRECISION array, dimension (K)
              TAU(i) must contain the scalar factor of the elemen-
              tary reflector H(i), as returned by DGEQRF.

      WORK    (workspace) DOUBLE PRECISION array, dimension (N)

      INFO    (output) INTEGER
              = 0: successful exit
              < 0: if INFO = -i, the i-th argument has an illegal

              value